readahead: combine file_ra_state.prev_index/prev_offset into prev_pos
Combine the file_ra_state members
unsigned long prev_index
unsigned int prev_offset
into
loff_t prev_pos
It is more consistent and better supports huge files.
Thanks to Peter for the nice proposal!
[akpm@linux-foundation.org: fix shift overflow]
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/filemap.c b/mm/filemap.c
index 5dc18d7..bbcca45 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -879,8 +879,8 @@
cached_page = NULL;
index = *ppos >> PAGE_CACHE_SHIFT;
next_index = index;
- prev_index = ra.prev_index;
- prev_offset = ra.prev_offset;
+ prev_index = ra.prev_pos >> PAGE_CACHE_SHIFT;
+ prev_offset = ra.prev_pos & (PAGE_CACHE_SIZE-1);
last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
@@ -966,7 +966,6 @@
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;
prev_offset = offset;
- ra.prev_offset = offset;
page_cache_release(page);
if (ret == nr && desc->count)
@@ -1056,9 +1055,11 @@
out:
*_ra = ra;
- _ra->prev_index = prev_index;
+ _ra->prev_pos = prev_index;
+ _ra->prev_pos <<= PAGE_CACHE_SHIFT;
+ _ra->prev_pos |= prev_offset;
- *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
+ *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
if (cached_page)
page_cache_release(cached_page);
if (filp)
@@ -1396,7 +1397,7 @@
* Found the page and have a reference on it.
*/
mark_page_accessed(page);
- ra->prev_index = page->index;
+ ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
vmf->page = page;
return ret | VM_FAULT_LOCKED;